title: Type II protein secretion by Pseudomonas aeruginosa: genetic suppression of a conditional mutation in the pilin-like component XcpT by the cytoplasmic component XcpR.
abstract: Pseudomonas aeruginosa exports a number of hydrolytic enzymes and toxins using the type II or general secretion pathway, found in a variety of Gram-negative bacteria and requiring the functions of at least 12 gene products (XcpP-Z and PilD/XcpA in P. aeruginosa). A number of these gene products are homologues of components of the type IV pilus biogenesis system, including four proteins, XcpT-W, which are highly similar to the pilin subunit in their size, localization and post-translational modifications. These proteins, in addition to the pilin subunit, are cleaved and methylated by the PilD/XcpA prepilin peptidase, but their interactions with other components of the export apparatus are unclear. Using a medium developed for the selection of export-proficient P. aeruginosa strains, we have isolated temperature-sensitive mutations in the xcpT gene and extragenic suppressors for one of the mutants. These suppressors fall into two classes, one that maps outside of the xcpP-Z gene cluster and may define additional cellular functions that are required for export, and a second that maps to the xcpR gene product and indicates a potential protein-protein interaction connecting two different cellular compartments and required for the assembly or function of the export apparatus.
authors.affiliation: Department of Microbiology, University of Illinois, Urbana 61801, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Kagami
authors.forename: M
authors.initials: M
authors.lastname: Ratliff
authors.forename: M
authors.initials: M
authors.lastname: Surber
authors.forename: A
authors.initials: A
authors.lastname: Martinez
authors.forename: D N
authors.initials: DN
authors.lastname: Nunn
mesh_terms: D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics*; D015153:Blotting, Western; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics; D026901:Membrane Transport Proteins; D016296:Mutagenesis; D009154:Mutation; D010957:Plasmids / Q000737:chemistry; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000502:physiology*; D013489:Suppression, Genetic / Q000502:physiology*
chemical_list: D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D002352:Carrier Proteins; D026901:Membrane Transport Proteins; C082104:XcpT protein, Pseudomonas aeruginosa; C082573:xcpR protein, Pseudomonas aeruginosa